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| From | Terje Mathisen <terje.mathisen@tmsw.no> |
| Newsgroups | comp.arch.arithmetic |
| Subject | Re: Napier's Bones versus Booth Encoding |
| Date | Sun, 15 Jun 2014 16:30:49 +0200 |
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Quadibloc wrote: > 128K bytes of memory will contain a 256 by 256 multiplication table, > and FF times FF is FE01. > > Thus, with a table lookup for every 8 bits of the multiplicand, two > input terms can be generated for *eight* bits of the multiplier, > which *doubles* the efficiency achieved with Booth encoding! > > And it's not as if you need an associative memory either, the two > numbers being multiplied just index into the table. > > I am not so presumptuous as to think that this is a *new* idea on my > part; no doubt others have thought of it, and it has a name, but I > haven't noticed anyone mentioning it. Name: Table lookup? I bet there was a bunch of old machines without HW multipliers which did just this, probably based on bcd digits, i.e. 160 bytes (with 60 empty slots) give you the regular multiplication table. I don't see where Booth give you any additional gains though, please explain! Terje -- - <Terje.Mathisen at tmsw.no> "almost all programming can be viewed as an exercise in caching"
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Napier's Bones versus Booth Encoding Quadibloc <jsavard@ecn.ab.ca> - 2014-06-15 07:00 -0700
Re: Napier's Bones versus Booth Encoding Terje Mathisen <terje.mathisen@tmsw.no> - 2014-06-15 16:30 +0200
Re: Napier's Bones versus Booth Encoding Quadibloc <jsavard@ecn.ab.ca> - 2014-06-15 09:28 -0700
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